diff --git a/packages/cli/src/gemini.ts b/packages/cli/src/gemini.ts
index 2cecbedb..29d2b1b7 100644
--- a/packages/cli/src/gemini.ts
+++ b/packages/cli/src/gemini.ts
@@ -101,10 +101,10 @@ async function start_sandbox(sandbox: string) {
   const args = ['run', '-it', '--rm', '--init', '--workdir', workdir];
 
   // mount current directory as ${workdir} inside container
-  args.push('-v', `${process.cwd()}:${workdir}`);
+  args.push('--volume', `${process.cwd()}:${workdir}`);
 
   // mount os.tmpdir() as /tmp inside container
-  args.push('-v', `${os.tmpdir()}:/tmp`);
+  args.push('--volume', `${os.tmpdir()}:/tmp`);
 
   // mount paths listed in SANDBOX_MOUNTS
   if (process.env.SANDBOX_MOUNTS) {
@@ -130,7 +130,7 @@ async function start_sandbox(sandbox: string) {
           process.exit(1);
         }
         console.log(`SANDBOX_MOUNTS: ${from} -> ${to} (${opts})`);
-        args.push('-v', mount);
+        args.push('--volume', mount);
       }
     }
   }
@@ -200,29 +200,38 @@ async function start_sandbox(sandbox: string) {
   const nodeArgs = [];
   const debugPort = process.env.DEBUG_PORT || '9229';
   if (process.env.DEBUG) {
-    args.push('-p', `${debugPort}:${debugPort}`);
+    args.push('--publish', `${debugPort}:${debugPort}`);
     nodeArgs.push(`--inspect-brk=0.0.0.0:${debugPort}`);
   }
 
   // open additional ports if SANDBOX_PORTS is set
   // also set up redirects (via socat) so servers can listen on localhost instead of 0.0.0.0
-  let bash_cmd = '';
+  let bashCmd = '';
   if (process.env.SANDBOX_PORTS) {
     for (let port of process.env.SANDBOX_PORTS.split(',')) {
       if ((port = port.trim())) {
         console.log(`SANDBOX_PORTS: ${port}`);
-        args.push('-p', `${port}:${port}`);
-        bash_cmd += `socat TCP4-LISTEN:${port},bind=$(hostname -i),fork,reuseaddr TCP4:127.0.0.1:${port} 2> /dev/null & `;
+        args.push('--publish', `${port}:${port}`);
+        bashCmd += `socat TCP4-LISTEN:${port},bind=$(hostname -i),fork,reuseaddr TCP4:127.0.0.1:${port} 2> /dev/null & `;
       }
     }
   }
 
+  // specify --user as "$(id -u):$(id -g)" if SANDBOX_SET_UID_GID is 1|true
+  // only necessary if user mapping is not handled by sandboxing setup on host
+  // (e.g. rootful docker on linux w/o userns-remap configured)
+  if (['1', 'true'].includes(process.env.SANDBOX_SET_UID_GID ?? '')) {
+    const uid = execSync('id -u').toString().trim();
+    const gid = execSync('id -g').toString().trim();
+    args.push('--user', `${uid}:${gid}`);
+  }
+
   // append remaining args (image, bash -c "node node_args... cli path cli_args...")
   // node_args and cli_args need to be quoted before being inserted into bash_cmd
   const quotedNodeArgs = nodeArgs.map((arg) => quote([arg]));
   const quotedCliArgs = process.argv.slice(2).map((arg) => quote([arg]));
-  bash_cmd += `node ${quotedNodeArgs.join(' ')} ${quote([cliPath])} ${quotedCliArgs.join(' ')}`;
-  args.push(image, 'bash', '-c', bash_cmd);
+  bashCmd += `node ${quotedNodeArgs.join(' ')} ${quote([cliPath])} ${quotedCliArgs.join(' ')}`;
+  args.push(image, 'bash', '-c', bashCmd);
 
   // spawn child and let it inherit stdio
   const child = spawn(sandbox, args, {
diff --git a/scripts/sandbox_command.sh b/scripts/sandbox_command.sh
index 03163458..fab94b52 100755
--- a/scripts/sandbox_command.sh
+++ b/scripts/sandbox_command.sh
@@ -22,15 +22,15 @@ set -euo pipefail
 QUIET=false
 while getopts ":q" opt; do
     case ${opt} in
-        q ) QUIET=true ;;
-        \? ) echo "Usage: $0 [-q]"
-            exit 1
-            ;;
+    q) QUIET=true ;;
+    \?)
+        echo "Usage: $0 [-q]"
+        exit 1
+        ;;
     esac
 done
 shift $((OPTIND - 1))
 
-
 # if GEMINI_CODE_SANDBOX is not set, try to source .env in case set there
 # allow .env to be in any ancestor directory (same as findEnvFile in config.ts)
 if [ -z "${GEMINI_CODE_SANDBOX:-}" ]; then
@@ -57,10 +57,10 @@ fi
 
 # if GEMINI_CODE_SANDBOX is set to 1 or true, then try to use docker or podman
 if [[ "${GEMINI_CODE_SANDBOX:-}" =~ ^(1|true)$ ]]; then
-    if command -v docker &> /dev/null; then
+    if command -v docker &>/dev/null; then
         if [ "$QUIET" = false ]; then echo "docker"; fi
         exit 0
-    elif command -v podman &> /dev/null; then
+    elif command -v podman &>/dev/null; then
         if [ "$QUIET" = false ]; then echo "podman"; fi
         exit 0
     else
@@ -69,7 +69,7 @@ if [[ "${GEMINI_CODE_SANDBOX:-}" =~ ^(1|true)$ ]]; then
     fi
 fi
 
-if ! command -v "$GEMINI_CODE_SANDBOX" &> /dev/null; then
+if ! command -v "$GEMINI_CODE_SANDBOX" &>/dev/null; then
     echo "ERROR: missing sandbox command '$GEMINI_CODE_SANDBOX' (from GEMINI_CODE_SANDBOX)" >&2
     exit 1
 fi
diff --git a/scripts/start.sh b/scripts/start.sh
index b6b94085..c979205e 100755
--- a/scripts/start.sh
+++ b/scripts/start.sh
@@ -30,4 +30,4 @@ else
     else
         CLI_VERSION='development' DEV=true node ./packages/cli "$@"
     fi
-fi
\ No newline at end of file
+fi
diff --git a/scripts/start_sandbox.sh b/scripts/start_sandbox.sh
index 444efbd3..b857d496 100755
--- a/scripts/start_sandbox.sh
+++ b/scripts/start_sandbox.sh
@@ -44,10 +44,10 @@ fi
 run_args=(-it --rm --init --workdir "$WORKDIR")
 
 # mount current directory as $WORKDIR inside container
-run_args+=(-v "$PWD:$WORKDIR")
+run_args+=(--volume "$PWD:$WORKDIR")
 
 # mount $TMPDIR as /tmp inside container
-run_args+=(-v "${TMPDIR:-/tmp/}:/tmp")
+run_args+=(--volume "${TMPDIR:-/tmp/}:/tmp")
 
 # if .env exists, source it before checking/parsing environment variables below
 # allow .env to be in any ancestor directory (same as findEnvFile in config.ts)
@@ -81,7 +81,7 @@ if [ -n "${SANDBOX_MOUNTS:-}" ]; then
                 exit 1
             fi
             echo "SANDBOX_MOUNTS: $from -> $to ($opts)"
-            run_args+=(-v "$mount")
+            run_args+=(--volume "$mount")
         fi
     done
 fi
@@ -130,7 +130,7 @@ run_args+=(--env "SANDBOX=$IMAGE-$INDEX")
 node_args=()
 if [ -n "${DEBUG:-}" ]; then
     node_args+=(--inspect-brk="0.0.0.0:$DEBUG_PORT")
-    run_args+=(-p "$DEBUG_PORT:$DEBUG_PORT")
+    run_args+=(--publish "$DEBUG_PORT:$DEBUG_PORT")
 fi
 node_args+=("$CLI_PATH" "$@")
 
@@ -142,13 +142,20 @@ if [ -n "${SANDBOX_PORTS:-}" ]; then
     for port in $ports; do
         if [ -n "$port" ]; then
             echo "SANDBOX_PORTS: $port"
-            run_args+=(-p "$port:$port")
+            run_args+=(--publish "$port:$port")
             bash_cmd+="socat TCP4-LISTEN:$port,bind=\$(hostname -i),fork,reuseaddr TCP4:127.0.0.1:$port 2> /dev/null& "
         fi
     done
 fi
 bash_cmd+="node $(printf '%q ' "${node_args[@]}")" # printf fixes quoting within args
 
+# specify --user as "$(id -u):$(id -g)" if SANDBOX_SET_UID_GID is 1|true
+# only necessary if user mapping is not handled by sandboxing setup on host
+# (e.g. rootful docker on linux w/o userns-remap configured)
+if [[ "${SANDBOX_SET_UID_GID:-}" =~ ^(1|true)$ ]]; then
+    run_args+=(--user "$(id -u):$(id -g)")
+fi
+
 # run gemini-code in sandbox container
 if [[ "$CMD" == "podman" ]]; then
     # use empty --authfile to skip unnecessary auth refresh overhead